Third instar larvae were obtained from the western cherry fruit ¯y rearing facility at the Yakima Agricul-
tural Research Laboratory after emerging from ®eld-collected unsprayed cherries. Infested cherries were placed on a wire screen and emerging larvae collected into a plastic pan of water. Once removed from the water, larvae became active and pupated in the petri dishes within 24 h. During this period, the fruit ¯y larvae were exposed to an equivalent of a 106/m2 concentration of infective juvenile nematodes in petri dishes (100 3 15 mm) that were lined with 9.0-cm-diameter Fisherbrand (P5) ®lter paper. Twenty larvae were selected randomly for each replicate plate. Dis-tilled water (0.2 ml) was pipetted into all dishes to moisten the ®lter paper. One milliliter of the appropri-ate nematode suspension (6360 IJ/ml) was then added to each dish. Depending on availability of larvae, three to four replicate plates were used per nematode species and controls. Bioassays were repeated on two separate dates.